The present invention relates to a data communications system and a data communications method. More to particularly, this invention relates to a data communications system and a data communications method wherein digital communication data is arranged into data packet before being transmitted.
In recent years, in the data communications system and the data communications method, it tends to use digital signal. For instance, the AV (Audio-Video) data which had been treated by the user as the analog data in the past. At present, the AV data is treated by the user as the digital data itself. In recent years, the AV data is treated as the digital data itself due to spread of digital satellite broadcast, internet communication, DVD (Digital Video Desk) and so forth. Further, IEEE 1394 high speed serial bus which is capable of transmitting digital data in high speed is made practicable. Thus, it is capable of easily transmitting the AV data with high quality among equipments. It is capable of delivering such the high quality AV data to the user.
A conventional data communications system and a data communications method have a configuration shown in FIG. 1. The data communications system and the data communications method execute transmission of the data in accordance with timing chart shown in FIG. 2. Referring to FIG. 1, a conventional transmission equipment fundamentally consists of a data acquisition means 210, a packet controller 220, a transmission controller 230, and a physical layer 240. A conventional reception equipment fundamentally consists of a data processor 250, a data reception means 260, a transmission controller 270, and a physical layer 280.
These transmission equipment and reception equipment are connected with each other by a transmission line. The data acquisition means 210 acquires the digital AV data through the media (not illustrated), for instance, the broadcast media of the digital satellite broadcast or so forth, the communication media of the internet or so forth, or the storage media such as the DVD or so forth.
The packet controller 220 arranges the above digital AV data into the packet-shaped data (hereinafter referred to as data packet). The transmission controller 230 executes transmission control of the data packet. The physical layer 240 sends out the data packet to the transmission line. The physical layer 280 receives the data packet from the transmission line. The transmission controller 270 implements reception control of the above data packet. The data reception means 260 forms digital AV data while linking these data packets. The data processor 250 executes processing of the digital AV data. Here, the data processing is selection of the digital AV data, demodulation of the digital AV data, D/A conversion of the digital AV data, video display of the digital AV data, audio regeneration of the digital AV data, and so forth. There are two kinds of the transmission modes of the packet transmission in the cases where IEEE 1394 is used for the transmission line. Such the two kinds of transmission modes are an asynchronous type transmission mode for transmitting a control instruction and so forth and a synchronous type transmission mode for transmitting the AV data and so forth, whose transfer band is guaranteed.
In the synchronous type transmission, it is capable of being invariably executed one time of transmission in every one transfer cycle, for instance, in every 125 xcexcsec. For that reason, the delay time and the transfer band are guaranteed. Thus, it is capable of transmitting the picture and the sound and so forth of real time without quality deterioration.
However, in the data communications method constituted in such the above described conventional technique, there is the problem that when the transmission line is initialized during data communications, the communication is interrupted. For instance, referring to FIG. 2, a bus reset occurs on the transmission line, disappearance of the data packet occurs on the transmission line, thus, it is incapable of receiving a part of the data packet on the reception side. Namely, only the picture sources S1, S3, and S4 within the picture sources S1, S2, S3, and S4 are received, and the picture source S2 can not be received caused by the fact that the picture source S2 is in the course of occurrence of the bus reset. As a result thereof, when it causes the picture source received by the reception equipment to be processed, the situation occurs that it is incapable of regenerating the picture corresponding to the picture source S2. For that reason, the regenerated picture is interrupted.
The proposal for resolving problem in relation to above described bus reset is well known. However, it is incapable of avoiding disappearance of the packet. For instance, the official report of the Japanese Patent Application Laid-Open No. HEI 8-18584 discloses technique that connection information of the equipment maintained beforehand, when the bus reset occurs during data communications, it causes connection of the equipment to be executed again on the basis of the maintained connection information. However, it is incapable of avoiding disappearance of the data packet during the bus reset too.
As is clear from the above description, in the conventional data communications method, there is the problem that a part of the packet is lost during the bus reset.
In view of the foregoing, it is an object of the present invention, in order to overcome the above mentioned problem, to provide a data communications system and a data communications method which are capable of avoiding disappearance of the digital AV data which is arranged into the data packet.
According to a first aspect of the present invention, in order to achieve the above mentioned object, there is provided a data communications system which comprises an initialized state detector for monitoring state of a transmission line whether or not the transmission line is an initialized state, a data storage means for storing therein an inputted data before outputting the data, and a timing controller, when the initialized state detector detects that the transmission line is under the initialized state, the timing controller causes control instruction to be issued for stopping output of the data temporarily in order to store the data in the data storage means, while when the initialized state detector detects the state that initialized state of the transmission line is released, the timing controller instructs that it causes data including the stored data to be outputted, wherein the data communications system enables disappearance of the transmit data to be prevented, which disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
Consequently, it is capable of preventing disappearance of the transmit data. The disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
According to a second aspect of the present invention, in the first aspect, there is provided a data communications system, which further comprises a data acquisition means for acquiring data from storage medium such as a DVD, a hard disk or the like and/or data medium such as an internet or the like, a packet controller for arranging data acquired by the data acquisition means into a data packet, and a transmission controller for controlling transmission of the data which is made the data packet by the packet controller, wherein, as to a communication means using a packet switching system to be efficient in data transmission, the data communications system enables disappearance of the transmit data to be prevented, which disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
Consequently, in the communication means using the packet switching system to be efficient in the data transmission, it is capable of preventing disappearance of the transmit data. The disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
According to a third aspect of the present invention, in the second aspect, there is provided a data communications system, which further comprises a second transmission controller for controlling data transmitted through the transmission line, a data reception means for receiving data selected by the transmission controller, and a data processor for implementing compound processing of the data received by the data reception means, wherein even though it causes initialization of the transmission line to be executed during data transfer, it is capable of transmitting the whole data without losing the data, and the packet which is used for transmission has a sequence property, thus it is capable of preventing a reversal of the sequence in compound processing.
Consequently, even though it causes initialization of the transmission line to be executed during data transfer, it is capable of transmitting the whole data without losing the data. The packet which is used for transmission has a sequence property, thus it is capable of preventing a reversal of the sequence in compound processing.
According to a fourth aspect of the present invention, in the first aspect, there is provided a data communications system, wherein there is provided a means for achieving function as a bridge for a plurality of transmission lines by the fact that it causes the data received by said data reception means through said second transmission controller to be used as the data should be inputted to said data storage means.
Consequently, since it becomes possible to communicate in the mutual transmission lines while separating respective transmission lines, it becomes possible to increase the number of the equipments connectable to the transmission line. Further, it is capable of holding interruption condition caused by the initialization of the transmission line within the transmission line concerned, thus it is capable of preventing influence thereof from spreading to the whole network.
According to a fifth aspect of the present invention, there is provided a data communications method which comprises the steps of an initialized state detecting step for monitoring state of a transmission line whether or not the transmission line is under initialized state, a data storing step for storing inputted data before outputting, and a timing controlling step when the initialized state detecting step detects that the transmission line is under the initialized state, the timing controlling step causes control instruction to be issued for stopping output of the data temporarily in order to store the data in the data storing step, while when the initialized state detecting step detects the state that initialized state of the transmission line is released, the timing controlling step instructs that it causes data including the stored data to be outputted, wherein the data communications method enables disappearance of the transmit data to be prevented, which disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
Consequently, it is capable of preventing disappearance of the transmit data. The disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
According to a sixth aspect of the present invention, in the fifth aspect, there is provided a data communications method, which further comprises the steps of a data acquiring step for acquiring data from storage medium such as a DVD, a hard disk or the like and/or data medium such as an internet or the like, a packet controlling step for arranging data acquired by the data acquiring step into a packet, and a transmission controlling step for controlling transmission of the data which is made the data packet by the packet controlling step, wherein, as to a communication step using a packet switching method to be efficient in data transmission, the data communications method enables disappearance of the transmit data to be prevented, which disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
Consequently, in the communication process using the packet switching system to be efficient in the data transmission, it is capable of preventing disappearance of the transmit data. The disappearance of the transmit data occurs caused by temporal interruption condition according to initialization of the transmission line.
According to a seventh aspect of the present invention, in the sixth aspect, there is provided a data communications method, which further comprises the steps of a second transmission controlling step for controlling data transmitted through the transmission line, a data reception step for receiving data selected by the transmission controlling step, and a data processing step for executing compound processing of the data received by the data reception step, wherein even though it causes initialization of the transmission line to be executed during data transfer, it is capable of transmitting the whole data without losing the data, and the data packet which is used for transmission has a sequence property, thus it is capable of preventing a reversal of the sequence in compound processing.
Consequently, even though it causes initialization of the transmission line to be executed during data transfer, it is capable of transmitting the whole data without losing the data. The packet which is used for transmission has a sequence property, thus it is capable of preventing a reversal of the sequence in compound processing.
According to an eighth aspect of the present invention, in the fifth aspect, there is provided a data communications method, wherein there is provided a step for achieving function as a bridge to a plurality of transmission lines by the fact that it causes the data received by the data reception step through the second transmission controlling step to be used as the data should be inputted to the data storing step.
Consequently, since it becomes possible to communicate in the mutual transmission lines while separating respective transmission lines, it becomes possible to increase the number of the equipments connectable to the transmission line. Further, it is capable of holding interruption condition caused by the initialization of the transmission line within the transmission line concerned, thus it is capable of preventing influence thereof from spreading to the whole network.